Nuclear envelope Volume

The ER is a continuous network of membranous tubular and lamellar structures in the cytosol (1, 2). The membranes that build up the organelle can constitute more than 95% of the total cellular membranes, and the total volume of the organelle can compose about 10% of cell volume, e.g., in hepatocytes. Although the ER is a single, spatially continuous compartment, it can be divided structurally and functionally into different subdomains. The ER forms contact sites beside the nuclear envelope with practically all the other organelles and the plasma membrane these junctional regions might have specific composition... 

The nucleus is a large membrane-bound cell organelle which houses the chromosomes and which occupies roughly 10% of the volume of all eukaryotic cells. The nucleus is separated from the rest of the cell and the cytoplasm by a double membraue known as the nuclear envelope. The outer layer of the nuclear membrane is studded with small openings called nuclear pores, which allow for the controlled movement of selected molecules in and out of the nucleus. Most of a eukaryotic cell s DNA is found in the chromosomes of the nucleus, while a very small amount of DNA is present in the mitochondria. All plant and animal cells with a nucleus and known as eukaryotic cells, (meaning true nucleus) while bacterial cells which lack a nucleus are known as prokaryotic cells. 

It is well known that lymphocytes are spherical, and have a thin cell membrane and a spherical nucleus (surrounded by a thin nuclear envelope) that occupies about 60% of the cell volume (188). Therefore, the dielectric properties of lymphocytes can be described by the double-shell model (188, 190, 191)(see Fig. 49). In this model the cell is considered to be a conducting sphere covered with a thin shell, much less conductive than the sphere itself, in which a smaller sphere with a shell (i.e., the nucleus) is incorporated. In addition, one assumes that every phase has no dielectric losses and the complex dielectric permittivity can thus be written as ... 

The intent of this chapter is not to survey noninvasive surface spectroscopy but to illustrate briefly how it is applied to resolve the Stummian issue of whether inner-sphere surface complexes form. For this purpose, the application of electron spin resonance (ESR), electron nuclear double resonance (ENDOR), and electron spin echo envelope modulation (ESEEM) spectroscopies to elucidate metal cation speciation and the use of extended X-ray absorption fine structure (EXAFS) spectroscopy to detect surface anion species will be described. Emphasis will be on the interpretation of spectra. Sample preparation and instrumentation details were reviewed in recent volumes edited by Hawthorne (55) and Perry (27). Because the constant capacitance model was developed in the context of adsorption by hydrous oxides, these... 

Intrinsic molecular volume, or the volume of the envelope of atomic spheres, can easily be calculated. Let N be the number of atoms in a molecule, with nuclear positions Xj reckoned in some reference frame, say the inertial reference frame. Let Ri be the atomic intermolecular non-bonding radius of atom i, briefly called henceforth the atomic radius. Let nj be the distance between the nuclei of two atoms joined by a chemical bond. Whenever ry is smaller than the sum of atomic radii, the sphere of atom i cuts into the sphere of atom j a spherical cap of height /ly. Molecular volume, Vm, can be calculated [8,10] by computing the total volume of the atomic spheres and subtracting the volumes of the intersecting caps ... 

Nuclear motion drags along the electronic cloud, so that as temperature rises, molecular envelopes oscillate more and more. If the intermolecular potential were perfectly harmonic, the overall volume effect would be nil, because the compressions and expansions would average out but the potential is much steeper on the compression side (Fig. 4.4), so expansion is hindered less than contraction and molecules effectively occupy more and more space as mobility increases. So thermal expansion is very strictly dependent on the shape of the potential curve, that is on the strength and anisotropy of the intermolecular potential, in a typical structure-property relationship. The simple equation that defines the isobaric thermal expansion coefficient a is... 

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